The least expensive models don't have any frills and have the basic components shown in my drawing. There is also a light switch and a light fixture, with a 40 watt appliance bulb.

The compressor, in the bottom part of the refrigerator, the condensor, shown in red, the evaporator, shown in blue, and the connecting refrigerant tubing are part of a closed system and normally does not need any attention. Most folks think that when their box is on the "fritz" it needs Freon¨ but generally this is not the problem. Most repairs require replacing simple, electrical controls and devices or simply cleaning out a stopped up drain.

This basic type of refrigerator is a manual defrost model with a static condensor mounted on the back. It's a good idea to clean the condensor now and then and keep the box far enough away from the wall to allow an inch or more of space between the condensor and the wall -- this part gets warm and needs to have ventilation to get rid of the heat it has absorbed from inside the box.

When this box has problems, it is usually due to a bad cold control (it's not called a thermostat), the starting relay that is mounted on the compressor, a bad wire or connection, or in some cases, a bad light switch which lets the bulb stay on when the door is closed.

This model has to be manually defrosted. As a serviceman, I've had calls to repair the evaporator (in the freezer compartment) because some idiot used a screwdriver or icepick to chip away at the ice instead of wating for the ice to melt. If the repair is made immediately, this can be fixed. However, this problem is usually caused by brain-dead RENTERS, who also try to hide it, and if it is not fixed right away, the compressor will be damaged.

Fan-Cooled Condensors

This makes a refrigerator more efficient because a fan circulates air over the condensor to get rid of heat removed from inside the box. The condensor is moved to the bottom of the refrigerator, and a fan blows across the coils. The condensor coils get dirty much faster and need to be cleaned more often (every spring is recommended). If the fan motor fails, the box will not cool properly. Some models, especially Admiral¨, used a plastic fan blade and in the cooler months, mice often find their way under the refrigerator and the plastic blade will break when it hits the mouse. A metal blade will usually stop turning when it hits a mouse, but in both cases, the fan motor usually needs to be replaced.

Self-Defrosting Refrigerators

These boxes don't need manual defrosting because they automatically defrost themselves. To do so, several devices are added:

• Defrost timer (defrosts every 4, 8, or 12 hours)
• Defrost thermostat (terminates defrost when ice is gone)
• Defrost heater (melts ice on the evaporator coil)
• Defrost drain (for water from ice melted during defrost)
• Evaporator fan motor (circulates cold air in the box)
• Switch(es) for evaporator fan motor (not all models)

• Amp probe and a line splitter
• Volt/Ohm meter

Defrost Timer

The first thing to check is the defrost timer. It is similar to a clock, and if the motor that advances it fails, the defrost cycle will not be started, or maybe it will stay in defrost and not go back into the cooling mode.

The defrost timer is about 6 inches square and about 2 inches thick. It could be located under the box, in front or back. Some models of Whirlpool and Kenmore locate it behind the cover over the light inside the box. Westinghouse is often inside the cooler compartment, in the top. Some Gibson boxes put it in the back, about chest high. It's often hidden, but every self-defrosting refrigerator has one, except for a few models of Whirlpool and Kenmore with factory-installed ice makers -- these models have an icemaker which also has the defrost timer built into it.

The timer will have a stem that protrudes, or may be flush, which you can turn using a large blade screwdriver. Mark the position with a pencil, then turn it until it "clicks." This should start the defrost mode. The defrost mode will continue for 10 to 30 minutes, depending on the design. If after 20 minutes, the refrigerator has not restarted, or the timer stem has not moved, the timer is bad.

When replacing the timer, you must use the correct one. There are about a dozen different configurations with even more types of connections. I sugguest you order the part by make, model number, and serial number of your refrigerator to make sure you get the right one. Depending on your brand, and where you purchase the part, the price may be from $20 to $40 for this part.

Defrost Thermostat and Heater . . .

If the defrost timer is working, turn the dial until defrost mode is activated. Use a line splitter at the wall plug and connect the refrigerator. Use an amp probe to check the load on one line. If the heater is working, the reading will be several amps. The amount of current draw depends on the make and model, but if it's under one amp, the heater or thermostat is probably bad.

On top mounted freezer models, both of these components are normally located under the freezer compartment, and requires removal of the panel at the bottom of the freezer to gain access. Some models may have some or all of the components in the very back -- a little investigating may be necessary. Often, the breaker trim has to be removed, too. These are plastic or vinyl trim pieces that snap in place. Remove them by carefully prying up. The panel that you will remove often contains many screws of different lengths. Take care to mark these so you can put them back in the same place.

Side-by-side refrigerators are similar, but the components, mentioned above, will be located in the back, or in the side between the cooler and freezer compartments. Some older boxes have bottom mounted freezers with a door or drawer -- if you have one of these, you'll have to look and see which panel can be removed to gain access to the evaporator coil area.

The defrost thermostat is about an inch in diameter and about 3/4 inch high, with two wires attached. This is cliped or clamped into place near the evaporator coil and senses when all the ice is melted. If there is ice on the coils and where the t-stat is located, disconnect the two wires and check for continuity. An ohm meter should give a reading of zero (0), indicating the switch is closed.

The defrost heater is fairly large, often similar to the shape of an electric oven element. Disconnect the two leads and use an ohm meter to test. If it's good, there will be some resistance, but the reading will be close to continuity. If the meter doesn't budge, the heater is bad.

The defrost heater may cost $25 or more, while the defrost thermostat may cost about $10 or so. The actual price may vary, depending on the make and model, and where you buy the parts.

If the defrost heater and thermostat test good and the box is not defrosting, the contacts inside the defrost timer may be bad. To check this, you will need to check for voltage at the heater with the refrigerator plugged in and the timer in the defrost mode. If no voltage is detected, replace the timer and check again. It is possible that a wire may be damaged and that is why we check to see if the new timer makes the heater come on.

Evaporator Fan Motor

When the refrigerator is in the cooling mode, this fan motor blows air across the evaporator coils and distributes it throughout the box. The easiest way to test for normal operation is to turn on the refrigerator, check to be sure the timer is in the cool mode, then open the door of the freezer compartment. If there is a push button switch near where the door closes, push it in and see if the fan runs. If it doesn't run, check in the cooling compartment for another switch. On some models, two sitches are used, or one switch that has double contacts may be used. This only allws the fan to run when the door is closed. Before taking the freezer compartment apart to get to the fan motor, check all the switches to make sure they are good. If you are not sure, temporarily bypass the switch and see if the fan runs.

If the evaporator fan motors doesn't run, is stalled, or is noisy, it should be replaced. Some folks try to oil them and make them last -- this is false economy and the motor should be replaced.

The normal operation of the evaporator fan motor allows it to run all the time, except for when in the defrost mode, or when the door is open, if there is a switch. Many newer models don't have a switch in the door and on hot, humid days, it will appear as if steam comes out of the freezer -- this is normal.

Defrost Drain

If the drain gets clogged with debris, slime, or mold, the water from defrosting will not drain out and as soon as the compressor turns on, the water will refreeze and the air will not be able to flow across the evaporator coils. Also, the fan motor may be damaged due to the ice build up. It's easiest to follow the drain from the drip pan, which normally sets on top of the condensor coils in the bottom of the refrigerator. It may be made of metal or plastic. Some refrigerators let the water drip down the back of the refrigerator, then out of the bottom. Others have a tube that runs out the back of the box from the freezer compartment.

If the drain is clogged, unstop it and advance the defrost timer to let the defrost cyle operate. Repeat this two or three times.